Refining trunk injection strategies for control of foliar insects and disease in Michigan apple orchards

Airblast sprayers are commonly used in apple orchards to apply pesticides. However, a majority of product is lost to the environment due to overspray or drift. This impacts non-target pests in the ecosystem, causing monetary loss for growers. Precise delivery of systemic products reduces the overall amount of active ingredient necessary for control. Trunk injection is widely used for control of emerald ash borer and for pest and disease control in urban settings. Previously, work at MSU showed trunk injection to also be effective at controlling foliar pests and diseases in apple orchards. Injections can provide insect and disease control that lasts beyond the first season, possibly eliminating the need to inject in the second. In the 2013 and 2014 seasons, injections were made to control apple scab, apple rust mite, brown marmorated stink bug, coddling moth, European red mite, green apple aphid, Oriental fruit moth, potato leaf hopper, rosy apple aphid, and spotted tentiform leaf miner. Efficacy was evaluated with field observations and bioassays, paired with GC/MS residue analysis. Different injection tools were compared for time of application, trunk wounding, and effective product delivery. In addition, nectar and pollen samples were analyzed to determine the presence/absence of pesticides and their metabolites. This paper expands upon previous research by refining timing, pesticide rates, and combined insecticide/fungicide injections in order to demonstrate the practicality of trunk injection technology in commercial orchards.